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Identification of anaerobic bacteria causing blood stream infections (BSI) is challenging. This study describes the epidemiology of anaerobic BSI at a tertiary care hospital and the performance of a rapid method for identification of anaerobic bacteria from blood cultures over three years, between June 2015 and June 2018. Short-term culturing is a low-cost user-friendly method and may be used for rapid identification of bacteria from positive blood cultures by matrix-associated laser desorption ionization time of flight (MALDI-TOF). Short-term culturing is performed after Gram staining on all positive blood culture bottles (BCBs) before 10:30 a.m. in our laboratory. Successful short-term cultures were defined as growth and reliable MALDI-TOF result in maximum 8 h after culture positivity. Data pertaining to unique anaerobic episodes and short-term cultures was collected retrospectively from our laboratory information system. Overall, during the three-year period, 692 unique anaerobic episodes (including Propionibacterium spp) were isolated. A total of 17 anaerobic bacterial genera were isolated in our laboratory, with 5 GNB genera and 12 GPB genera. The most prevalent bacteria were Bacteroides spp. 266/692 (38%) , Propionibacterium spp. 128/692 (18%), Clostridium spp. 103/692 (15%) , Fusobacterium spp. 34/692 (5%), and Actinomyces spp. 34/692 (5%). We performed short-term cultures on 270/564 (48%) clinically relevant episodes (excluding Propionibacterium spp) on chocolate agar plates. Growth within 8 h from culture positivity was detected in 33/270 (12%) short-term cultures. There were 22/33 (67%) gram negative (GNB) and 11/33 (33%) gram positive bacteria (GPB). Only two genera were identified: Bacteroides spp 22/33 (67%) and Clostridium spp 11/33 (33%). Thus, short-term culturing can function as a low-cost add-on to already existing protocols involving MALDI-TOF, where both GNB and GPB can be identified. • Bacteroides spp. (38%), Propionibacterium spp. (18%) and Clostridium spp (15%) were most common. • Short-term culture followed by MALDI-TOF MS can function as an add-on to conventional methods. • The method could identify 67% of Bacteroides spp. and 33% of Clostridium spp. within 8 h. [ABSTRACT FROM AUTHOR]

There are several approaches available for purifying microorganisms prior to matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) analysis. In the present study, rapid BACpro® II (Nittobo Medical Co., Ltd., Tokyo, Japan), a new application, has been compared with Sepsityper® kit (Bruker Daltonics, Billerica, USA) and an in-house method. Samples were also tested with two modules, standard and Sepsityper®, identified in the Bruker MALDI-TOF MS. The bottles having monomicrobial growth were included in the study according to Gram staining results. In total, two hundred blood culture bottles were included but there was no growth in one of the subcultures so 199 blood culture bottles were studied prospectively. With the standard MALDI-TOF MS analysis, rapid BACpro® II could successfully identify microorganisms in 174/199 (87.4%) of the bottles where Sepsityper® kit and in-house method were successful in 136/199 (68.3%) and 114/199 (57.3%), respectively. When the MALDI-TOF MS data were analysed by Sepsityper® module, the identification rates were increased to 94.4%, 82.1% and 69.8% (p < 0.001), respectively. In the Sepsityper® module, 72/73 (98.6%) of Gram-negative and 97/106 (91.5%) of Gram-positive microorganisms were detected by rapid BACpro® II method. The present study shows that rapid BACpro® II is a reliable preparation procedure and has higher rates of identification compared with Sepsityper® kit and in-house method. The use of the Sepsityper® module in blood cultures increases the chance of identification for all three methods studied. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to compare the performance of four methods that are widely used in the clinical microbiology laboratory for identification of Pasteurella species. The 4 methods evaluated were VITEK2, VITEK MS (BioMerieux), and Bruker Biotyper MS (Bruker) as well as traditional biochemical tests. Sequencing of the sodA gene was used as the reference method. Sixty-five isolates of Pasteurella spp. from 65 patients were analyzed. One Pasteurella multocida isolate from American Type Culture Collection (Manassas, VA, USA) was used as a reference. Traditional biochemical tests accurately identified 62/66 (94%) isolates. Both Bruker and Vitek matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) identified 59/66 (89%) strains, but VITEK2 could only identify 32/66 (48.5%) isolates correctly. The mean time to identification using biochemical tests was 20 hours; VITEK2 took 6 hours and MALDI-TOF approximately 10 minutes. In conclusion, MALDI-TOF is a quick method, which accurately identified most isolates of Pasteurella to the species level. Thus, MALDI-TOF constitutes a valuable diagnostic tool in the clinical laboratory. [Copyright &y& Elsevier]